[Qemu-devel] Segfault in block driver with qemu-system-ppc and -M mac99

[Mark Cave-Ayland]

Hi all,

Whilst running through some OpenBIOS tests, I came across the following 
segfault in qemu-system-ppc with -M mac99 on git master. It is 
consistently reproducible here with my test openSUSE image although 
strangely all my other images seem to run fine. The host is running 
amd64 Debian Wheezy.


address@hidden:~/rel-qemu-git/bin$ gdb --args ./qemu-system-ppc -cdrom 
/home/build/src/qemu/image/ppc/openSUSE-11.1-NET-ppc.iso -boot d -g 
1024x768x32 -vnc :1 -m 512 -M mac99
GNU gdb (GDB) 7.4.1-debian
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/build/rel-qemu-git/bin/qemu-system-ppc...done.
(gdb) handle SIGUSR1 nostop noprint
Signal        Stop      Print   Pass to program Description
SIGUSR1       No        No      Yes             User defined signal 1
(gdb) run
Starting program: /home/build/rel-qemu-git/bin/qemu-system-ppc -cdrom 
/home/build/src/qemu/image/ppc/openSUSE-11.1-NET-ppc.iso -boot d -g 
1024x768x32 -vnc :1 -m 512 -M mac99
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffdf197700 (LWP 17230)]
[New Thread 0x7fffde996700 (LWP 17231)]
[New Thread 0x7fffbc9e8700 (LWP 17232)]
[Thread 0x7fffdf197700 (LWP 17230) exited]

Program received signal SIGSEGV, Segmentation fault.
0x00005555555ef458 in bdrv_co_do_readv (bs=0x0, sector_num=169, 
nb_sectors=0, qiov=0x55555661f878, flags=0) at block.c:2240
2240        BlockDriver *drv = bs->drv;
(gdb) bt
#0  0x00005555555ef458 in bdrv_co_do_readv (bs=0x0, sector_num=169, 
nb_sectors=0, qiov=0x55555661f878, flags=0) at block.c:2240
#1  0x00005555555f3a28 in bdrv_co_do_rw (opaque=0x555556620030) at 
block.c:3837
#2  0x0000555555631fa4 in coroutine_trampoline (i0=1448744496, i1=21845) 
at coroutine-ucontext.c:138
#3  0x00007ffff508c020 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#4  0x00007fffffffb100 in ?? ()
#5  0x0000000000000000 in ?? ()
(gdb)


It seems as if the BlockDriver pointer is coming back as NULL - does 
anyone have any ideas as to what could be causing this?


Many thanks,

Mark.